Sizing synthetic linear polyamide textiles



Patented Apr. 27, 1943 SIZING SYNTHETIC LINEAR POLYAMIDE TEXTILES John E. Bristol, Niagara Falls, N. 1., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application December 6, 1941, Serial No. 421,957

18 Claims.

This invention relates to an improved method of sizing yarns composed of synthetic linear fiber-forming polymers, more particularly synthetic linear polyamides, and the improved products resulting therefrom.

The term synthetic linear polyamide" as used throughout the specification and claims is intended to refer specifically to the materials disclosed in U. S. Patents Nos. 2,071,250, 2,130,523 and 2,130,948.

The sizing of yarns composed of synthetic linear fiber-forming polymers, and particularly synthetic linear polyamides, has, heretofore, given great difiiculty.

Although a very large number of satisfactory sizes have been developed for other yarns, very few sizes have been found which will adhere satisfactorily to yarnscomposed of filaments of synthetic linear polyamides. Such filaments are not only quite round and very smooth, but they are substantially water-insensitive.

The copending application of Edgar W. Spanagel, Serial No. 357,757, filed on September 21, 1940, discloses in great detail the critical requirements of a size suitable for use on the smooth, round, filament yarns composed of synthetic linear polyamides in the knitting of ladies sheer hosiery.

It has now been found that the sizing of synthetic linear polyamide yarn can be greatly improved, and that numerous sizes considered to be of little or no value for such synthetic linear polyamide yarns can be used to advantage, if the yarn is first provided with a suitable undercoating.

It is, therefore, an object of the present invention to provide an improved method of sizingyarns composed of synthetic linear fiber-forming polymers, and particularly synthetic linear polyamides.

It is another object of this invention to produce an improved sized yarn composed of synthetic linear fiber-forming polymers, and particularly synthetic linear polyamides.

It is a further object of this invention to provide a process whereby sizes, heretofore considered to be of little or no value for sizing yarns composed of synthetic linear fiber-forming polymers, can be used to advantage in sizing the same.

Other objects of the invention will appear hereinafter.

The objects of the invention may be accomplished by coating the yarn, prior to sizing the same with a tannic acid. The term a tannic acid" is meant to include gallic acid, di-gallic acid. and the various tannins. The tannic acid must be applied as a sub-coating, or under-coating. A mixture of the tannic acid with the size, or a coating of tannic acid on top of the size, will not produce the desired effects. 1

The following examples are given to illustrate preferred sizing compositions and preferred methods of applying the same. The details set forth in the examples are not, however, to be considered as limitative of the invention.

Example I centipoises in a 4% aqueous solution at 20 C.,

1.7% boric acid, and 90.3% water. Example II The method outlined in Example I is carried out with a30-denier, lo-filament, 30-turn polydecamethylene sebacamide yarn. The yarn has excellent knitting and snag resisting properties when knit into a sheer, full-fashioned stocking.

Example III A 30-denier, 10-filament, 2-turn yarn prepared from polyherzamethylene adipamide is put on an uptwister and given 28 turns additional twist while applying a .25% coat of tannic acid to the yarn ust subsequent to the twisting operation and just prior to the winding up of the 30-turn yarn by passing the BO-turn yarn through a dip trough containing an aqueous solution having 1% of tannic acid and 0.15% oxalic acid. After drying, the yarn is sized with a solution comprising 7.5% partially saponified polyvinyl acetate having a saponification number of approximately and a viscosity of approximately 5 centipoises in a 4% aqueous solution at 20 0., 1.6% boric acid, and approximately 90.9% water. The size is applied on-therun in a machine constructed much like a coning machine, but having a bobbin as the windup package. The size is applied by passing the yarn over a rotating roll dipping into a trough conthe fabric in a hot water solution containing 0.1%

hydrated trisodium phosphate, 0.1% oxalic acid, and 0.5% fatty alcohol sodium sulfate.

Example, IV

A 30-denier, 10-filament, 2-turn yarn prepared from polyhexamethylene adipamide is Put on an uptwister and given 28 turns additional twist while applying a 0.25% coat of tannic acid to the yarn just subsequent to the twisting operation and just prior to the winding up of the 30-turn yarn by passing the 30-turn yarn through a dip trough containing an aqueous solution comprising 1% of tannic acid and 0.15% oxalic acid. After drying, the yarn is sized with a solution comprising 7.5% partially saponified polyvinyl acetate having a saponification number of approximately 140 and a viscosity of approximately 5 centipoises in a 4% aqueous solution at 20 C., 1% polyethylene oxide having a molecular weight of approximately 1500, and approximately 91.5% water. The yarn is coned while being sized by applying 3.5% of olive oil. The resulting yarn is foundto knit well on a standard full-fashioned knitting machine. The size is removedby washyarn showed no tendency to lose size when the yarn was passed over the various guides and tension devices of the coning machine. It was knit into full-fashioned hosiery leg fabric on a 54 gauge full-fashioned hosiery knitting machine. The knitted fabric possessed excellent snag resistance.

Example IX A 30-denier, 10-filament, 30-turn polyhexamethylene adipamide yarn was subcoated with tannic acid as in Example VIII, dried, and sized with a 12% aqueous solution of a low substituted water-soluble starch acetate prepared from corn starch by boiling raw corn starch with three times its weight of glacial acetic acid for one hour. The sized yarn was knit on a 54 gauge full-fashioned" hosiery machine. The knitted fabric possessed excellent snag resistance.

Example X A SO-denier, 10-filament, 30-turn polyhexamethylene adipamide yarn was given a 0.8% coat of tannic acid as described in Example VII and dried. A topcoat was applied from an 11% aqueous solution of a water-soluble interpolymer prepared by interpolymerizing triglycol diamine,

I hexamethylene diamine, and adipic acid in such ing the fabric in a hot water solution containing I 0.1% hydrated trisodium phosphate, 0.1% oxalic acid, and 0.5% fatty alcohol sodium sulfate.

Example V The method outlined in Example-TV is'carried" out with a -denier, 10-filament, 2-turn polyd-ecamethylene sebacamide yarn. The yarn has excellent knitting and snag resisting properties when knit into a sheer, full-fashioned stocking..

' Example VI A SO-denier, lofilament, z-tum -polyhexamethylene sebacamide yarn is sized, dried, and coned in accordance with the method outlined in Example 'IV. The sized-yam has excellent knitting and snag resisting characteristics.

' Example VII A BO-denier. Ill-filament, 30-tu'rn polyhexamethylenecadipamide yarn was subcoated from a 1% solution of tannic acid containing 0.1%-

' sodium'oleyl sulfate as a wetting agent in suchhosiery fabric under conditions usually employed in the knitting of silk. The. knitted fabric possessed a high degree of snag resistance.

Example VIII v A 80--denie'r, :10-fllament, 30-tum polyhexamethylene adipamide. yarn was subcoated with a 3% solution of tannic acid containing 0.1% of sodium oleyl sulfate in such a manner as to deposit 0.8% tannic acid on the yarn. The yam wasdriedand a topcoat of size was applied from.

resistance.

a manner as to produce a polymer containing approximately 85%. polytriglycol adipamide and approximately 15% polyhexamethylene adipamide." The yam; was-knit on a 54' gauge fullfashioned hosiery fabric. The knitted fabric possessed excellent snag. resistance, whereas a fabricknit from a-s'ample of yarn sized with the same agentsfinTa similar manner, without the use ofatannic acid subecoat, showed poor snag f Ezrample XI "A. filmof .poljyhexamethylene adipamide was coated with'a 6% solutionof tannic acid containing 0.1% of sodium ole'yl; sulfate as a wetting agent. Thc film,- aftef'dryirig, was coated with a warm 5% solution orgeia mg Upon drying, the gelatin adhered very tenaciously to the base film and retained its goodadhesion characteristics over a long period, whereas a similar film coated with gelatin, without a tannic acid sub-coat, did

not adhere Welland, after two days standing at room temperature, was very easily scraped off ofthe film. 7 Example XII A film of' polyhexamethylene adipamide was coated with tannic acid as described in Example The film was allowed to dry at room temperature and was then coated with a 10% solution of hide glue. The glue adhered. excellently a 12% s'olutionof oxidized corn starch. The sized to the sub-coated base film and showed no tendency to loosen even after aging for one month.

,Onthe contrary,-glue applied to afllm without a. tannic acid sub-coat adhered well at first but after one day had peeled loose from the film.

Example XIII v A polyhexamethylene adipamide photographic film support was sub-coated with; an aqueous solution containing 3% tannic acid and 0.1% sodium lauryl sulfate. After the tannic acid subgelatin solution. After drying, 'a -milligram coating of a light-sensitive gelatin silver halide emulsion was applied to the gelatin sub-coat.

Example XIV A film of polyhexamethylene adipamide was coated with a 3% aqueous solution of tannic acid containing 0.1% sodium dodecyl sulfate. After drying, the film was coated with a photographic elatino-silver bromide emulsion in known manner. The coating was then allowed to air dry. The emulsion adhered very tenaciously to the film even upon tearing, whereas a similarly prepared film which was not sub-coated with tannic acid showed poor adhesion between the emulsion and the film base.

In sizing polyamide yarns, good results are obtained with 0.02% to 1.5% coats of tannic acid; and particularly good results are obtained when 0.05% to 0.3% coats of tannic acid are applied to the yarn; .but the anchor coat is not to be considered to be limited to these percentages. It will be apparent that numerous similar anchoring compounds may be useful as sub-coats on yarns to the end of more effectively binding the size composition to the yarn. It will also be apparent that numerous similar anchoring ma-- terials may be useful as sub-coats on other shaped. structures, such as films, pellicles, monofils, staple fibers, spun yarns, tubes, rods, molded articles, woven and knitted fabrics, and the like. This process is particularly important for photographic film since good adhesion is essential to the preparationof satisfactory photographic film and in general photographic emulsions do not adhere satisfactorily to synthetic linear polyamides. In view of the great problem of effecting adherence ofsizes and other film-forming materials to such water insensitive materials as the synthetic linear polyamides, the use of' the anchor coats of this invention constitutes an outstanding development inthis art, particularly in the sizing of yarns.

In addition to the film-forming sizing materials described in the examples, it has been round that the adherence of numerous other materials to the various synthetic linear polyamides can be increased by the application of tannic acid sub-coats in accordance with this invention; among these materials may be mentioned sodium cellulose glycollate, gum arabic, casein, soya protein, blood, blood albumin, egg albumin, gliadin, peanut protein, gum Madagascar, gum Shiraz, gum tragacanth, degraded starches of various types, such as hydrolized starch, British gum, dextrin, starch derivatives, such as methyl starch, glycol starch, starch glycollic acid, cellulose derivatives, such as glycol cellulose, cellulose acetate phthalate, various partially saponified polyvinyl acetates, polyvinyl alcohol, various acetals of polyvinyl alcohol derived from aldol, glyoxal, and formaldehyde, various other derivatives of polyvinyl alcohol, etc. Although the invention is broadly applicable to many other sizing agents, it is particularly applicable to polyhydroxy and protein film-forming sizing materials which are soluble in aqueous media. The principles of the present invention may be used in the application of the water-soluble, interpolymer sizing compositions disclosed in United States Patent No. 2,191,556, Exceptionally desirable results have been obtained with tannic acid under-coatings for polyvinyl alcohol sizes, particularly the sizes described and claimed in the copending applications of E. W. Spanagel, Serial No. 357,757, and

D. E. Strain, Serial No. 357,755, filed on September 21, 1940.

It will be apparent that the tannic acid subcoat can be applied by various other methods than those above-described, such as by impregnation, spray coating, or any of the other methods which are well known in the art for the application of thin layers to formed objects. Similarly,

' the-film-forming topcoat may be applied in numerous ways known to the art.

Various wetting agents may be used with the tannic acid in addition to that disclosed above. Similarly, various modifying agents may be incorporated in the tannic acid solution or in the solution of the topcoating composition for various purposes; for example, plasticizers, corrosion inhibitors, preservatives, wetting agents, fillers, and various other types of modifying agents may be used.

Although the coating compositions and the methods of this invention are unique and outstanding for the sizing and coating of synthetic linear polyamide articles, they will also be useful in the sizingof other yarns and fabrics and in the coating of various shaped articles, prepared from other. materials, for example, synthetic linear polyesters, polyethers, polyacetals, synthetic linear vinyl polymers, synthetic linear ethylene polymers, and numerous interpolymers of these and other synthetic linear fiber-forming polymers. The compositions and methods of this invention will be particularly useful for the coating of materials which are relatively water-insensitive; for the tannic acid tends to adhere well to such formed structures and to the topcoatings which have been disclosed above, whereas such topcoatings do not tend to adhere well when applied alone, directly to such water-insensitive articles from aqueous solutions.

It is, of course, within the scope of this invention to use solutions of other concentrations and to apply other percentages in the form of coatings than those specifically disclosed above. It is also within the scope of the invention to apply the anchor coat from solutions containing other solvents than water. It is also within the scope of the invention to apply two or more coats of the anchor coat or the topcoat.

The methods of this invention present a distinct advantage over the prior art methods of applying sizes and coatings to water-insensitive materials, such as synthetic linear polyamides in that numerous coating materials which ordinarily do not adhere well to polyamide articles are caused to adhere verytenaciously over long periods of time by the action of the anchor coat of tannic acid. The invention is particularly advantageous for the sizing of synthetic linear polyamide yarns, especially those which are to be used in the full-fashioned knitting of ladies sheer stockings; for the problem of size adherence to such yarns is very great because of the drastic action of the knitting machine needles and sinkers and the disastrous results of size accumulation on the knitting machine parts.

Since it is obvious that many changes, andpolymer which comprises applying thereto a coating or an anchoring agent containing a tannic acid, and applying to saidcoated structure a sizing composition.

2. The process oi sizing sheets, yarn and the like composed oi a synthetic linear fiber-forming polymer which comprises applying thereto a coating of a tannic acid, and applying to said coated structure a sizing composition comprising a polyhydroxy film-forming material soluble in aqueous media.

3. The process or sizing sheets, yarn and the like composed 01' a synthetic linear fiber-forming polymer which comprises applying thereto a coating of a tannic acid, and applying to said coated structure a sizing composition containing a partially saponifled polyvinyl acetate.

4. The process oi sizing sheets, yarn'and the like composed of a-synthetic linear fiber-forming polymer which comprises applying thereto a coating of a vtannic acid, and applying to said 6. The process of sizing sheets, yarn and the like composed ofva synthetic linear fiber-forming polymer which comprises applying thereto a or a tannic acid and an over-coating of a size comprising a polyhydroxy ilimei'orming-material soluble in'aqueous media.- j I 10. Synthetic linear flber i'orming polymer sheets, yarn and the like containing a coating of za tannic acid and an over-coating ot a size comprlsing'a partiallysaponiiled polyvinyl acetate. I

11. Synthetic linear fiber-forming polymer sheets, yarn and the like containing a coating of a tannic acid and an over-coatingof aslze containing'gelatin. v

12. Synthetic linear fiber-forming polymer sheets, yarn and the like containing a 0.02%to 1.5% coating of a tanniciacid and .an over-coating of a size. I u

13. Synthetic linear fiber-forming polymer sheets, yarn and the like containing a 0.02% to 1.5% coating of a tannic acid and an over-coating of a size comprising a polyhydroxy .fllmforming material soluble in aqueous 'media."

14. Synthetic linear fiber-forming polymer sheets, yarn and the like containing a 0.02% to 1.5% coating .of a-tannlc acid and an over-coating of a size comprising a partially saponifled' polyvinyl acetate.

15. The process of sizing sheets, yarn and the a like composed 'of a synthetic linear fiber-forming 0.02% to 1.5%coating of a tannic acid,'based on the weight of the uncoatedstructure, and. applying to said coated structure a sizing composition containing a polyhydroxy film-forming material soluble in aqueous media.

7. The process of sizing sheets, yarn and the like composed of a synthetic linear fiber-forming polymer which comprises applying thereto a 0.02% to 1.5% coating of a tannic acid, based on the weight of the uncoated structure, and apply-.

ing to said coated structure a sizing composition containing a partially saponifled polyvinyl acetate.

8. Synthetic linear fiber-forming polymer polymer which comprises applying thereto a coating of a tannic acid, and applying to said coated structure a sizing. composition comprising a protein film-forming material soluble in aqueous media."

16. The processor sizing sheets, yarnand-the like composed of a synthetic linear. fiber-dorming polymer which comprises applying thereto a 0.02% to 1.5% coating of: a tannic acid, based on the weight of the uncoated structure, and applying to said coated structure a sizing composition containing a protein-fllm-forming material soluble in aqueousmedla. I

17-. Synthetic fiber-forming polymer sheets, yarn and the like containing a coating of a tannic acid and an over-coating of a size comprising a protein film-forming material soluble in aqueous media.

18. Synthetic linear fiber-forming polymer sheets, yarn and .the like containing a 0.02% to 1.5% coating oi a tannic acid and an over-coating of a size comprising a protein film-forming material soluble in aqueous media.

. JOHN E. BRISTOL. 

